Dual solenoid controlled apparatus for preventing release of contaminants from an internal combustion engine



April 9, 1957 F. E. M KINLEY 2,787,939

DUAL SOLENOID CONTROLLED APPARATUS FOR PREVENTING RELEASE OFCONTAMINANTS FROM AN INTERNAL COMBUSTION ENGINE 1 Filed March 19, 1956 2Sheets-Sheet l 1 -92 llllllllkt Ell/9057' o 3 i INVENTOR.

Fun 5 flak war I Arm/mm Apnl 9, 1957 F. E. MOKINLEY 2,737,989

mum. souauom CONTROLLED APPARATUS FOR PREVENTING RELEASE OF CONTAMINANTSFROM AN INTERNAL COMBUSTION ENGINE Filed March 19, 1956 2 Sheets-Sheet 29i Y INVENTOR.

Fun 6''. Half/ 4 DUAE SOLENOID CoNTRoLLED APPARATUS FOR PREVENTINGRELEASE-.0171 CONTAMINANTS FROM AN INTERNAL COMBUSTION ENGINE Fred E.McKinley, Paramount, Calif.

Application March 19, 1956, Serial No;'572,276 'Clain1s.- (C1. 123-'11'9 Th'epresent invention relates generally to the field ofinternal-combustion engines and more particularly to a'novel apparatusfor preventingthe release of contamin'ants from the'exhaust thereof.

Itis well known that the exhaust gases issuing from the int'e'rnalCombustion engines of automotive vehicles constitute a prime source oftheso-called smog which exists in and around the principal populationcenters of-the cduntry. The harmful effects of this "smog uponboth'anirn'ate and inanimate objects isflike'wise very well known."Although manyforms of apparatus for preventing the release ofcontaminants from the exhaust gases of su'chengines havebeenheretofore-proposed, such devices have for various reasons proven tobe unsatisfactory andaccordinglyam not now in general usage.

lt'i's a major object oftlie present inventionto provide an effectiveapparatus for preventing the release of contaminants from the exhaust ofan internal combustion en ine. 7

Another object of the invention is to providean apparatus of theaforedescribed nature whichmaybe readily installed upon the engine ofany conventional automotive vehicle. g

It is another object of theinvntiod-to rovide-a paratus of theaforedescribed nature which includes means for re-cyclingexhaust gasthrough 'the'intakemanifold of the engine during deceleration:

Another object is to provide apparatus of theaforedescribed nature thatis'sim'ple'iri design -and rugged of construction whereby it may afford'a long and troublefree service life.- 1

his yet another object to provide-apparatus of this nature that isfoolproof and entirely *autoinatic'in operation.

A further object is to provide-apparatus of th'enfor'edescribed naturewhich does not in any. way; 'eifectthe operation of the engine during'other th'an'dec'eleration conditions.

Another object is to-provide apparatus of the aforedescribed naturewhichis compact in size andlight 'in weight. I v

These and other objects and advantages of thepresent invention willbecome apparent from the 'following detailed description, when takeninconjunction" with the appended drawings, wherein:

Figure '1 is a partially. diagrammatio side elevational view of apreferred form of apparatus embodying' -the present invention mountedupon --a coiiventional-internal combustion engine;

Figure 2 is a view similar to Figure 1 but showing the parts of theapparatus during deceleration of said engine;

Figure 3 is an enlarged fragmentary, vertical-sectional ,l'nite StatesPatentO Fatented Apr. 9, 1957 to the upper end of a curved by-p'ass pipe'12. The

lower end of the by-pass pipe 12 is rigidly securedto a T-fitting 14.The upper end of the T-fitting 14 is'connected to a flanged opening 16formed on th'eexhaust manifold E. The lower end of-the T-fitting 14 isrigidly secured to the front of the tail pipe *T. A fuel shutoff valve20 is mounted withinthe carburetor support-10 above the flanged opening11 so as to control communication between the carburetor C and theintake manifold I. A re-cycling valve 22 is also mounted within -thecarburetor support 10 adjacent the flanged opening 11. This re-cyclingvalve 22 controls communication between the by-pass pipe and the intakemanifold I.

Referring to Figure 1, during operation'of theengine E other thandeceleration, the fuel shut-oil valve; 20

'will be arranged in'an open position while the recycling valve 22 willbe arranged'in a closed position. Accordingly, the carburetor C will bein free communication with the intake manifold I while there-cycling'valvef2'2 'willprevent the flow of re-cycled exhaust gasintothe intake manifold 1. Referring now to Figure 2, during deceleration ofthe engine, however, the fuel shu'e'oif valve 20 will be arranged in aclosed position while the reycling valve 22 will be opened. Accordingly,during deceleration of the engine, the closed "fuel 'shut-oibvalve 20will prevent the flow of fuel from the carburetor C to the intakemanifold I while at the same time the opened re-cycling valve 22 willpermit 'exhaust'gases 'to be r'e-cycled from the exhaust manifold E intothe iiitake'manifold I.

More particularly, referring to Figuresl and 3, both the fuel shut-offvalve 20 and the re-cycling valve 22 maybe 'of the butterfly type. Othertypes of valves, however, may, also prove satisfactory, The fuel shutonvalve 22 is pivotally supported within the carburetor support 10 bymeans of a horizontal shaft 26. The recycling valve 22 is likewisepivotally supported within the carburetor support lfiby a second.horizontal'sha'f t '28; Externally of the carburetor support 10, theshaft 26 "is keyed to a crank 30. The horizontal shaft 28 of there-cycling valve 22'is' likewise keyed to a second crank 32 aligned withthe .firstcrank 30. The free ends of these cranks 30 and32 are pivotallyinterconnected by a rigid lever 34.. The shaft26 is also keyed to. a

, downwardly extending toggle arm 36. The lowerend of this'toggle arm is.pivotally-connected to the intermediate portion of a horizontallyextending, plunger rod 40, The two. end portions of this plunger rodv 40are aflixed to the armatures (not shown) of a pairofelecf tric solenoids.42 and 44. These solenoids 42 ancl 44 are rigidly 'aflixedto thecarburetor support 10.- The lowerend offthe toggle arm 36.is alsosecured to the loivvr 'end of atensionspring 46. The upper endof thistension spring 46 is rigidly secured to the-side of .the carburetorsupport 10.

andsis connected to the carburetorC by suitablepouventional linkage.This linkage, includes ahhorizont all y extending; longitudinally Tmovable? rod 56, bumper memberSS is rigidly afiixedto this rod. 56.Theupper end of the bumper member 58 carries a set screw 60. The frontend of the set screw 60 is aligned with an actuator button 62 thatprotrudes from the rear of the switch 50. As indicated in Figure l, atsuch time as the accelerator pedal is depressed, the set screw 60 willbe spaced rearwardly and out of engagement with the microswitch button62. Referring now to Figure 2, when the accelerator pedal A is released,however, the rod 56 will be moved to its forward position so that theset screw 60 engages and depresses the microswitch button 62.

A low output circuit closing switch 70 forms another component of theapparatus. As indicated in Figure 4, this switch '70 includes a switchelement 74 which is normally biased towards a closed position by asuitable spring 76. The switch element 74 is adapted to be retained inan open position upon adequate energization of the windings 78 of asolenoid 80, the armature 82 of this solenoid being connected to theswitch 74. One side of the windings 78 are grounded by a lead 84 whilethe other side is connected by a lead 86 to the ungrounded terminal ofthe generator G. One side of the switch element 74 is connected to thewindings of the right-hand solenoid 42 by a lead 88. The opposite sideof the switch element 74 is connected by a lead 90 to the vehiclesbattery 92.

Referring now to Figure 5, the solenoids 42 and 44 ,are of identicalconstruction. They incorporate an elec- .tric switch element 94 that isnormally biased to a closed -.position, as indicated in this figure. Theelectric current flowing to the windings 98 from the battery 92 willthereby be automatically cut off.

Referring again to Figures 1 and 2, the upper terminal 100 of the switch50 is connected by a lead 102 to the windings of the left-hand solenoid44. The other side of these windings are grounded by a lead 104. Thecenter terminal 106 of the switch 50 is connected by a lead 108 to thevehicles battery 92. The lower terminal 110 of the switch 50 isconnected by a lead 112 to the righthand solenoid 42, the lead 112intersecting the lead 88 from the low output closing switch 70. Theother side of these windings are grounded by a lead 114.

In the operattion of the aforedescribed apparatus and referring toFigure 1, assuming the vehicles driver is exerting downward pressureupon the accelerator pedal A, the set screw 60 of the bumper member 58will be spaced rearwardly from the switch button 62. Accordingly,current will be free to flow from the battery 92 through lead 108 to thecenter terminal 106 of the switch 50. At this time the center terminal106 will be connected to the lower terminal 110 and accordingly thiscurrent will be free to fiow through lead 112 to the windings of theright-hand solenoid 42. This current will not actually flow to thesolenoid windings, however, inasmuch as the solenoids switch element 94will be in an open position. Assuming that the rotational speed of thegenerator G is above idling at this time, the switch element 74 of thelow output circuit closing switch 70 will likewise be open. Thus,current cannot flow from lead 90 through to lead 88 to the windings ofthe solenoid 42. The plunger rod 40 and hence the toggle arm normalcommunication will exist between the carburetor C and the intakemanifold I, while the flow of exhaust gases into the intake manifoldwill be effectively blocked by the closed re-cycling valve 22.

Referring now to Figure 2 and assuming that the ve hicle is undergoingforward motion, when the driver releases the accelerator pedal A so asto decelerate, the set screw 60 will engage and depress the switchbutton 62. This will cut oil? the flow of current to the lower terminal110 of the microswitch 50 from the center terminal 106, and insteadconnect the center terminal 106 to the upper terminal 100. Accordingly,current will be free to fiow from the battery 92 through lead 102 to thewindings of the left-hand solenoid 44. The latter will be therebyenergized so as to retract the plunger rod 40 into the solenoid 44. Asthe plunger rod is so retracted, its actuating pin 96 will open itsswitch element 94 and thereby cut oft further flow of current to thesewindings. Once the plunger rod 40 has been urged into its position ofFigure 2, the toggle spring 46 will positively retain it therein. Thismovement of the plunger rod 40 will close the fuel shut-off valve 20 andconcurrently open the re-cycling valve 22. Accordingly, the flow of fuelfrom the carburetor C into the intake manifold I will cease.Concurrently, exhaust gases will be free to recycle from the exhaustmanifold E into the intake manitold I. Under these conditions, thecontaminants usually produced by the conventional engines duringdeceleration due to the existence of an excess of fuel within thecombustion chambers will not be produced. Additionally, the intakemanifold I will be maintained in a heated and dry condition by therecycled exhaust gases. Accordingly, when the fuel shut-off valve 20 isagain opened, the fuel flowing into the intake manifold will besufficiently vaporized as to undergo immediate combustion. Theintroduction of exhaust gas within the intake manifold I below the fuelshut-ofi valve 20 also prevents the fuel from being drawn around theperiphery of the fuel shut-off valve due to the high vacuum normallycreated within the intake manifold during deceleration of the engine. 7

Assuming that the vehicle comes to a stop with the accelerator pedalreleased, the electric current generated by the generator G willgradually decrease. As the current decreases, the spring 76 of the lowoutput circuit closing switch 70 will eventually overcome the weakeningforce of the windings of the solenoid 78 whereby the switch element 74will move to a closed position. Electric current will then flow from thebattery 92 through leads and 88 to the windings of the right-handsolenoid 42 so as to energize these windings. Upon such energization,the plunger rod 40 will be returned to the right to its originalposition so as to thereby re-open the fuel shut-off valve 20 andconcurrently close the re-cycling valve 22. The closing movement of theplunger rod 40 will serve to open its switch element 94 whereby the flowof current to the windings of the solenoid 42 will be cut off.

Assuming that the vehicle is again accelerated after a decelerationperiod without coming to a stop, the switch element 74 of the low outputcircuit closing switch 70 will not be closed. When the accelerator pedalA is again depressed, the set screw 60 will be retracted from the switchbutton 62. Accordingly, current from the battery 92 will no longer flowfrom the center terminal 106 of the switch to the upper terminal thereofbut instead will fiow from the center terminal to the lower terminal110. This will effect momentary energization of the right-hand solenoid42 so as to return the plunger rod 40 to the right. In this manner, thefuel shut-off valve 20 will be reopened while the re-cycling valve 22will be concurrently closed.

Although the intake manifold I is shown as being connected to aconventional carburetor, it will be apparent that various other fuelingdevices may be employed such as a conventional fuel injectionarrangement. It will also be apparent that various other modificationsand changes may be made with respect to the foregoing descriptionwithout departing from the spirit of the invention or the scope of thefollowing claims.

l Apparatusfor preventin grrelease of contaminants from the exhaust ofan internal combustion engine duringsdeceleration, said engine includingan intake manifold, a carburetor and an accelerator, comprising: a fuelshut-otf-valve interposed between said carburetor and said intakemanifold; fluid conduit means interconnecting said exhaust and saidintake manifold; a re-cycling valve interposed in said fluid conduitmeans; first solenoid means operatively connected to said valves andwhich when energized concurrently moves said fuel shut-off valve to anopen position and said re-cycling valve to a closed position;secondsolenoid means operatively connected to saidvalves and which whenenergized concurrently moves said fuel shut-off valve to a closedposition and said re-cycling valve to an open position; an, electricswitch operable by said accelerator for effecting energifzation of saidfirst solenoid means when said accelerator is depressed and foralternately effecting energization of said second solenoid means whensaid accelerator is released; electric conduit means for conductingcurrent to said solenoid means, said-electric conduitmeans beingconnected to said electric switch; a second electricv switch interposedin said electric conduit means and which when closed will effectenergization of: said first solenoid, said second electric, switchnormally beingrnaintainedopen; and means for automatically closing saidsecond electric switch when the rfotationalspeedof said engine fallsbelow a predetermined value whereby said first solenoid means will beenergized even though said accelerator is released.

.2. Apparatus for preventing release of contaminants from the. exhaustof an internal'combustion engine during deceleration, saidengine'including an intake manifold; a. carburetor and an accelerator,comprising: a fuel shut-off valve interposed between said carburetor andsaid intake'manifold; fluid conduitmeans interconnecting said exhaustand said intake manifold; a re-cycling valve interposed in' said fluidconduit means; first solenoid means operatively connected to said valvesand which when energized concurrently moves said fuel shut-off valve toan open position and said re cycling valve' to a closed position; secondsolenoid means operatively connected to said valves and which whenenergized cor'icurrently moves 1 said fuel shut-off valve to a closedposition. and said re-cycling valve-to anopen position; spring'means forretaining'said fuel shut-off valve in'an open position aud -saidre-cycling valv'e Y in a'close'd position'o'r alternately retaining saidfuelshut-oif' valve ina closed position and said re-cycling valvein"an"open position; an'electric switch operable by said accelerator foreffecting energization of said first solenoid means when saidaccelerator is depressed and'for alternately elfecting energization of'said second solenoid means when said accelerator is released; electricconduit means forconductin'g current to said solenoid means, saidelectric conduit means being connected to said electric switch; a'secondelectric switchinte'rposed in said electric conduit means and whic hwhenclosed will effect energization'of said first solenoid, said secondelectric switch normally being maintained" open; and means forautomatically closing 'said secon d electric switch when' th'erotational-speed of said engine falls below" a predetermined valuewhereby said-first solenoid means will be energized even though saidaccelerator is released.

,3IAppara'tu's' for preventing release of contaminants from'the' exhaustof an internal combustion engine during deceleration, said engineincluding an intake manifoldfalcarburetor and an accelerator,comprising: a fuel shiit-ol'fvalve interposed between said carburetorandsaid intake manifold; fluid conduitme'ans'interconnecting said exhaustand said intake manifold; a recycling valve interposed in said fluidconduit means; first'solenoidmeans operatively connected to said valvesand which when energizedconcurrently moves said fuel shut-off valve toan openposition and said re-cyclingvalve to a closed posh dons secondsolenoid ineansoperatively connected to said valves and which 'whe nenergized concurrently movessaid fuel shut-off valve to aclosed-position and said re-cycling valve to an open position;-anelectric switch operable by said accelerator for effecting encrgizationof said first solenoid means when said accelerator is depressed and foralternately effecting energization of said second solenoid' means whensaid accelerator is released; electric conduit means for conductingcurrent to said solenoid means, said electric conduit means beingconnected with said electric switch; a second electric switch interposedin said electric conduit means and which when energized will elfectenergization of said first solenoid,said second electric switch normallybeing maintained open; means for automatically stopping the flow' ofelectric current to said solenoid means after they have moved saidvalves from one position to another; and means for automati callyclosing saidsecond electric switch when the rotational speed of saidengine falls below a predetermined value whereby said first solenoidmeans will be energized eventhough'said accelerator is released.

4. Apparatus forpreventing release of contaminants fromth e exhaust ofan internal combustion engine duringdeceleration, saidengine includingan intake mani: fold, a carburetor and an accelerator, comprising: afuel shut-off valve interposed between said carburetor and said intakemanifoldyfluid conduit means interconnecting said exhaustand said intakemanifold; a recycling valve interposed in said fluid conduit means;first solenoid means operatively connected to said valvesand whichwhenenergized concurrently moves said fuel shut-otf valve to an openposition and said re-cycling valve to a closed position; second solenoidmeans operatively connected to said valves andwhich when energizedconcurrently moves sa'id fuel shutoff valve to a closed position andsaid re-cycling valve to an open position;spring' means for retainingsaid fuel shut-off valve-in an open position and said re-cycling valvein a closed position or alternatelyretaining said fuel shut-off valve ina closed position and said re-cycling valve in an open position; anelectric switch operable by said accelerator for effecting energizationof said first solenoid-means when said accelerator is depressed and foralternately effecting energization of said second solenoid m eanswhensaid accelerator is released; electric conduit means for conductingcurrent to said solenoid means, said electric conduit means beingconnected with said electric switch; a second electric switch interposedin said electric conduit means and which when'energized will effectenergization of said firstsolenoid, said second electric switch normallybeing maintained open; means for automatically stopping-the flow ofelectric current to said solenoid means after they have movedsaid valvesfrom one position to another; and means for automatically closing saidsecond electric switch when the rota tional speed of said engine fallsbelow a predetermined value whereby said first solenoid means will beenergized even though said accelerator is released. j

- S ApparatuS for preventingrelease of contaminants from the exhaust ofan internal combustion engine'during-deceleratio'n, said engineincluding an intake manifold, a carburetor, a generator andan'accelerator, coniprising: 'a fuel shut-off valve interposed betweensaid carburetor and saidiintake manifold; fluid conduit meansinterconnecting)saidexhaust and said intake manifold; a re cyclingvalveinterposed in said fluid conduit means; first solenoid means operativelyconnected to said valves and which when energized concurrently movessaid fuel ,shut-ofl valveto an open position and said recycling valve toa closed position; secondsolenoid means operatively eonnectedto saidvalves and which when energized concurrentlymovessaid fuel shut-offvalve to a closed p o' sition and said recycling valve to an openposition; an electr switch operable by said accelerator for effectingenergization of said first-solenoid means' when"saidac-- 7 t. celeratoris depressed and for alternately effecting energization of said secondsolenoid means when said accelerator is released; electric conduit meansfor conducting current to said solenoid means, said electric conduitmeans being connected with said electric switch; and a low outputcircuit closing switch interposed in said electric conduit means forconducting electric current to said first solenoid means only when therotational speed of said engine falls below a predetermined value, saidswitch including a switch element, resilient means normally biasing saidswitch element closed, a solenoid having windings connected to saidgenerator and an armature secured to said switch element.

6. Apparatus for preventing release of contaminants from the exhaust ofan internal combustion engine during deceleration, said engine includingan intake manifold, a carburetor, a generator and an accelerator,comprising: a fuel shut-off valve interposed between said carburetor andsaid intake manifold; fluid conduit means interconnecting said exhaustand said intake manifold; a recycling valve interposed in said fluidconduit means; first solenoid means operatively connected to said valvesand which when energized concurrently moves said fuel shutoff valve toan open position and said re-cycling valve to a closed position; secondsolenoid means operatively connected to said valves and which whenenergized concurrently moves said fuel shut-off valve to a closedposition and said recycling valve to an open position; toggle springmeans for retaining said fuel shut-off valve in an open position andsaid re-cycling valve in a closed position or alternately retaining saidfuel shut-off valve in a closed position and said re-cycling valve in anopen position; an electric switch operable by said accelerator foreffecting energization of said first solenoid means when saidaccelerator is depressed and for alternately eflecting energization ofsaid second solenoid means when said accelerator is released; electricconduit means for conducting current to said solenoid means, saidelectric conduit means being connected with said electric switch; and alow output circuit closing switch interposed in said electric conduitmeans for conducting electric current to said first solenoid means onlywhen the rotational speed of said engine falls below a predeterminedvalue, said switch including a switch element, resilient means normallybiasing said switch element closed, a solenoid having windings connectedto said generator and an armature secured to said switch element.

7. Apparatus for preventing release of contaminants from the exhaust ofan internal combustion engine during deceleration, said engine includingan intake manifold, a carburetor, a generator and an accelerator,comprising: a fuel shut-off valve interposed between said carburetor andsaid intake manifold; fluid conduit means interconnecting said exhaustand said intake manifold; a re-cycling valve interposed in said fluidconduit means; first solenoid means operatively connected to said valvesand which when energized concurrently moves said fuel shutoff valve toan open position and said re-cycling valve to a closed position; secondsolenoid means operatively connected to said valves and which whenenergized concurrently moves said fuel shut-off valve to a closedposition and said re-cycling valve to an open position; an electricswitch operable by said accelerator for effecting energization of saidfirst solenoid means when said accelerator is depressed and foralternately effecting energization of said second solenoid means whensaid accelcrator is released; electric conduit means for conductingcurrent to said solenoid means, said electric conduit means beingconnected with said electric switch; means for automatically stoppingthe flow of electric curlCntlO said solenoid means after they have movedsaid valves from one position to another; and a low output circuitclosing switch interposed in said electric conduit means for conductingelectric current to said first solenoid means only when the rotationalspeed of said engine falls below a predetermined value, said switchincluding a switch element, resilient means normally biasing said switchelement closed, a solenoid having windings connected to said generatorand an armature secured to said switch element.

8. Apparatus for preventing release of contaminants from the exhaust ofan internal combustion engine during deceleration, said engine includingan intake manifold, a carburetor, a generator and an accelerator,comprising: a fuel shutoff valve interposed between said carburetor andsaid intake manifold; fluid conduit means interconnecting said exhaustand said intake manifold; a recycling valve interposed in said fluidconduit means; first solenoid means operatively connected to said valvesand which when energized concurrently moves said fuel shut-off valve toan open position and said re-cycling valve to a closed position; secondsolenoid means operatively connected to said valves and which when ener'gized concurrently moves said fuel shut-ofl valve to a closed positionand said re-cycling valve to an open position; toggle spring means forretaining said fuel shut-off valve in an open position and saidre-cycling valve in a closed position or alternately retaining said fuelshut-off valve in a closed position and said re-cycling valve in an openposition; an electric switch operable by said accelerator for effectingenergization of said first solenoid means when said accelerator isdepressed and for alternately effecting energization of said secondsolenoid means when said accelerator is released; electric conduit meansfor conducting current to said solenoid means, said electric conduitmeans being connected with said electric switch; means for automaticallystopping the flow of electric current to said solenoid means after theyhave moved said valves from one position to another; and a low outputcircuit closing switch interposed in said electric conduit means forconducting electric current to said first solenoid means only when therotational speed of said engine falls below a predetermined value, saidswitch including a switch element, resilient means normally biasing saidswitch element closed, a solenoid having windings connected to saidgenerator and an armature secured to said switch element.

9. Apparatus for preventing release of contaminants from the exhaust ofan internal combustion engine during deceleration, said engine includingan intake manifold, a carburetor and an accelerator, comprising: a fuelshut-off valve interposed between said carburetor and said intakemanifold; fluid conduit means interconnecting said exhaust and saidintake manifold; a recycling valve interposed in said fluid conduitmeans; electric solenoid means for moving said valves between a normalposition wherein said fuel shut-off valve is open and said recyclingvalve is closed and a second position wherein said fuel shut-off valveis closed and said re-cycling valve is open; an electric switch operableby said accelerator whereby said solenoid means will be free to movesaid valves to their first position when said accelerator is releasedand said solenoid means will be free to move said valves to their secondposition when said accelerator is depressed; electric conduit means forconducting current to said solenoid means, said electric conduit meansbeing connected to said electric switch; a normally open second electricswitch interposed in said electric conduit means and which when closedwill cause said solenoid means to move said valves to their firstposition; and means for automatically closing said second electricswitch when the rotational speed of said engine falls below apredetermined value.

10. Apparatus for preventing release of contaminants from the exhaust ofan internal combustion engine during deceleration, said engine includingan intake manifold, a carburetor and an accelerator, comprising: a fuelshut-off valve interposed between said carburetor and said intakemanifold; fluid conduit means interconnecting said exhaust and saidintake manifold; a rcelectric solenoid means for moving said valvesbetween a normal position wherein said fuel shut-offvalve is open andsaid re-cycling valve is closed and a second position wherein said fuelshut-off valve is closed and said recycling valve is open; toggle springmeans for retaining said valves in either position until they are againmoved by said solenoid means; an electric switch operable by saidaccelerator whereby said solenoid means will be free to move said valvesto their first position when said accelerator is released and saidsolenoid means will be free to move said valves to their second positionwhen said accelerator is depressed; electric conduit means forconducting current to said solenoid means, said electric conduit meansbeing connected to said electric switch; a normally open second electricswitch interposed in said electric conduit means and which when closedwill cause said solenoid means to move said valves to their firstposition; and means for automatically closing said second electricswitch when the rotational speed of said engine falls below apredetermined value.

No references cited.

